Thin Wall Molding

Thin wall molding produces very thin, lightweight plastic parts at high speed using specialized tooling, high injection speeds, and high clamp-force presses.

Overview

Thin wall molding (high-speed injection molding) is a specialized injection molding process for very thin sections and long flow lengths. It uses high-speed filling, elevated injection pressures, and robust, thermally optimized molds to produce lightweight parts with wall thicknesses typically in the 0.010–0.040" (0.25–1.0 mm) range. Cycle times are short, making it a strong fit for very high production volumes.

This process excels for parts where reduced wall thickness cuts material cost and weight, and where part stiffness can be recovered with ribs, bosses, and smart geometry. Tradeoffs include higher tooling cost, tighter processing window, and stricter design rules for flow, venting, and gate placement. Not every resin or geometry is suitable; materials must have good flow and thermal stability, and parts must avoid heavy sections that trap heat. When the design supports uniform thin walls and high annual volumes, thin wall molding delivers low cost per part and fast throughput.

Common Materials

  • Polypropylene (PP)
  • Polystyrene (PS)
  • Acrylonitrile Butadiene Styrene (ABS)
  • Polycarbonate (PC)
  • Nylon 6/6 (PA66)
  • High Impact Polystyrene (HIPS)

Tolerances

±0.002" to ±0.005" on critical dimensions, depending on part size and wall thickness

Applications

  • Disposable food containers and lids
  • Consumer electronics housings and bezels
  • Battery covers and small device enclosures
  • Medical device housings and trays
  • Thin packaging components and clamshells
  • Telecom and networking equipment covers

When to Choose Thin Wall Molding

Choose thin wall molding for high-volume production of lightweight plastic parts with wall thickness typically below 1 mm and long flow lengths. It fits best when the part can use ribs and geometry, rather than bulk wall thickness, to achieve stiffness and when you can justify higher tooling cost with large annual volumes.

vs Standard Injection Molding

Choose thin wall molding when you need significantly thinner walls, faster cycle times, and can design for long flow lengths with highly filled cavities. It suits high-volume programs where reduced part weight and material savings offset the more complex, higher-cost tooling.

vs Overmolding

Thin wall molding is better when the part is a single-material thin shell and you care most about speed, weight, and part cost. Overmolding is more appropriate when bonding multiple materials or creating soft-touch surfaces matters more than extreme wall thinness and cycle time.

vs Insert Molding

Pick thin wall molding for pure plastic thin-shell parts without embedded metal or electronics. Insert molding makes sense once you need to encapsulate inserts or contacts; thin wall molding prioritizes fast, repeatable production of lightweight, single-material parts.

vs Compression Molding

Thin wall molding is a better fit for thermoplastic parts with very thin, uniform walls and high annual volumes. Compression molding suits thicker sections, lower to medium volumes, or materials that do not flow well through thin sections at high speed.

vs Blow Molding

Choose thin wall molding for detailed, thin flat or shell-like parts with tight tolerances and features such as ribs, bosses, and snap-fits. Blow molding is better for hollow containers and bottles where continuous parison or preform inflation defines the geometry.

Design Considerations

  • Keep walls as uniform and thin as functionally possible; avoid thick sections that slow cooling and cause sink or warpage
  • Limit flow length-to-thickness ratios or add flow leaders and strategic gating to ensure complete fill at high speed
  • Use ribs, gussets, and geometry instead of thicker walls to achieve stiffness and reduce material usage
  • Add generous draft angles on all vertical faces to support fast ejection and minimize scuffing on thin features
  • Avoid sharp internal corners; use radii to improve flow, reduce stress concentration, and extend mold life
  • Call out realistic tolerances and clearly identify critical dimensions so molders can balance speed, pressure, and part stability